The present invention pertains to a buckle folding machine with a device for automatically setting the folding rollers to different folding gap widths as a function of the measured or calculated thickness of a sheet of paper or stack passing through the folding gap, wherein the folding rollers to be adjusted are mounted on pivoted levers, which are mounted coaxially in pairs and can be pivoted against permanent restoring forces under the effect of electrically controllable adjusting members and wherein the adjusting members are actuated by an electronic process computer, which calculates the folding gap widths to be set in the particular case according to a preset working program from measured paper thicknesses and/or types of folding and/or from paper thicknesses and/or types of folding entered manually.
In a prior-art paper folding machine of this type (e.g., DE-G 92 03 930.8), the folding rollers, which form a folding point each in pairs, are mounted in two-armed pivoted levers, which are present in pairs and can be moved apart against the action of radial spring forces.
These pivoted levers are actuated by adjusting members, by which the distances between the axes of the folding rollers can be set to different folding gap widths by means of self-locking, manually adjustable threaded engagements corresponding to the paper thickness to be processed and the number of paper layers passing through the individual folding points. To determine the folding gap widths of the individual pairs of folding rollers, a programmed process computer with an entry keyboard and a digital display is provided, in which the thickness and the sheet length of the material running in for folding is entered either manually or via electronic analog-digital converters from a thickness-measuring means or a length-measuring means and in which the desired type of folding and/or the set lead lengths of the individual lead limiters are entered.
The folding gap widths calculated by the process computer from the values entered are displayed as digital values and/or are fed in via a control device provided with electronic comparator circuits and power amplifiers. This control device controls gear motors of servo controllers, which bring about the continuous setting of the individual distances between the axes to these folding gap widths, which correspond to a single thickness or a multiple thickness of the material to be folded by means of the threaded engagements provided, and which have as actual value transducers electric or electronic position indicators which are connected to the respective adjusting members.
The thickness-measuring means and the length-measuring means are arranged in a transport path located between a sheet-separating means and an intake point formed by a roller pair. The folding rollers are arranged in relation to one another such that the axes of two folding rollers each are located in the corners of an isosceles rectangular triangle and that one folding roller of a folding roller pair is adjustable in the direction of one leg and the other in the direction of the other leg of the triangle. An optimal arrangement and mounting of the two-armed pivoted lever is thus achieved and it is guaranteed that the individual folding rollers can always be set to different folding gap widths trouble-free and unaffected by the other folding rollers.
Even though the adjusting members provided in this prior-art buckle folding machine, which are driven by electric gear motors and have threaded engagements via which the particular settings of the pivoted levers take place, do make possible an automatic, individual setting of the individual folding rollers, this setting is maintained in this prior-art buckle folding machine over a larger series of operations taking place in the same manner. It is not possible with this prior-art setting device to perform an adjusting of the folding rollers within the frequency of passage in the case of different paper and stack thicknesses immediately following one another.
The primary object of the present invention is to provide a buckle folding machine of the type described in the introduction, in which the setting of the folding rollers to different folding gap widths can take place very rapidly and also temporarily for even a very short duration.
This object is accomplished according to the present invention by the adjusting members consisting of a plurality of pneumatic working cylinders, which are arranged in a row in a cascade-like pattern and whose working strokes mutually add up.
Due to the design of the adjusting members according to the present invention and their pneumatic mode of operation, it is possible to change the particular settings of the individual folding rollers to certain folding gap widths in a rapid sequence corresponding to a high frequency of passage, and it is possible with other embodiments to set more standardized intermediate values between a minimum and a maximum folding gap width than the number of working cylinders in an adjusting manner.
For example, using three working cylinders arranged in an adjusting member, which have three different working strokes, it is possible to set eight different folding gap widths on a pair of rollers, in which pressure is admitted to the three working cylinders in different combinations.
An embodiment of the present invention is advantageous for actuating the individual working cylinders, because simple, reliable control elements operated at a high switching speed thus guarantee a reliable mode of operation.
A very simple, compact design with high reliability of operation, which can be manufactured without problems, is achieved with an embodiment of the invention.
An embodiment ensures the trouble-free admission of pressure and high speed of response of the individual working cylinders and their working pistons with simple means.
Due to the control valves being integrated in groups a clear, simple design of the control units is obtained, on which possible causes of disturbance care also be rapidly recognized.
An embodiment is also used to reach a high speed of response of the individual working cylinders.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.